The objective of this project is to investigate the neural control of hibernation. Hibernation is an extreme extension of the interactions between CNS mechanisms regulating body temperature and controlling arousal states in euthermic mammals. Therefore, we propose to use both EEG and unit recording techniques to describe changes in the activities of the hypothalamus, the limbic system, and the brainstem reticular formation throughout the events of hibernation with and without the application of stimuli to evoke thermoregulatory and arousal responses. We also shall describe the temperature sensitive characteristics of pre-optic anterior hypothalamic neurons in euthermic and hibernating hibernators. The advantages of the proposed research in comparison to past studies derives from the use of chronic, floating, low impedance microwire electrodes which enable the recording of the activities of many units over long periods of time in unanesthetized, unrestrained animals.